Liver failure is the 7th leading cause of death and is responsible for 50,000 deaths per year in the United States. Orthotopic liver transplantation is the only proven effective treatment of acute liver failure (ALF), but its use is limited due to organ donor shortage, associated high costs, and the requirement of lifelong immunosuppression. The present and expected growth of the population that is affected by liver failure is ever rising and a life-saving alternative to transplantation is needed to support patients. Bioartificial liver devices are a rational approach to support ALF patients as a bridge to transplantation. Five cell- based devices have been tested in humans and pigs and appear safe, but none have shown a survival benefit. The failure of devices to-date suggests an ineffective mechanism of action. End-stage liver failure leads to systemic dysfunction that is occurring simultaneously with an inflammatory response. We hypothesize that a combination approach to therapy that provides hepatocellular support along with cytoprotection, anti-inflammatory, and trophic support will cover the broad spectrum of pathological processes that can stabilize a patient. In proof-of-principle therapeutic trials, we have demonstrated that human mesenchymal stem cell (MSCs) naturally secrete bioactive molecules that have immunomodulatory properties. We have developed MSC-based devices that are operated outside the body and connect to a subject's circulation to provide long-term support, and have shown that when connected to one of these devices for 10 hours, rats undergoing ALF have a 5-fold increase in survival from less than 15% to over 70%. The overall goal of this Phase I project is to develop a composite cellular bioreactor for the treatment of ALF that integrates both hepatocyte and MSC metabolism and secretion in a single unit, and evaluate the added benefit of this two-cell device over and above the effectiveness of the MSC devices. The project specific aims are: (1) To optimize the in vitro coculture of MSCs and hepatocytes and simulate the effect of liver failure serum on the function of the coculture;and (2) To incorporate MSCs and hepatocytes into flat-plate devices and initiate therapeutic testing of bioreactor treatments in rodent models. Upon successful completion of this project, the deliverable will be a prototype cell-laden dialysis cartridge that can be readily scaled up and tested in large animals. PUBLIC HEALTH RELEVANCE: We propose to develop an extracorporeal bioartificial liver device that offers unparalleled support to patients undergoing liver failure. The device will contain hepatocytes and mesenchymal stem cells (MSCs). The addition of MSCs is unique to our technology and is designed to enhance the metabolic functions of hepatocytes exposed to plasma and restore the regulation of the dysfunctional immune system in patients undergoing liver failure by active MSC secretion anti-inflammatory and trophic molecules. This two-pronged approach distinguishes this device from current prototypes. Our objectives are to perform in vitro optimization of the coculture using metabolic engineering of the coculture and in vivo testing of a microfabricated coculture device in two rat models of liver failure. These studies will determine if the combination therapeutic approach can be indicated for a broad range of liver disease etiologies and will motivate testing in large animal models of liver failure, and ultimately in human patients.